1. Field of the Invention
This invention relates to the improvement of the anti-wear, anti-friction and oxidation residence performance of lubricants by use of additives and to the formulated lubricants exhibiting such improved performance characteristics.
2. Related Art
Wear and friction are among the major concerns in operating machinery having metal to metal contracting of moving parts.
To insure the long life and continued usefulness of such machinery as well as to reduce down time for repairs it is necessary that wear and friction at the metal to metal interfaces be kept to a minimum. This is accomplished by the use of various lubricant materials. Typical lubricants are oils and greases obtained from hydrocarbon sources such as petroleum, tar sands, coal, shale oil, etc. and more recently include liquid hydrocarbons produced by the isomerization of natural or synthetic waxes.
Such hydrocarbon oil or grease materials, however, regardless of source, at some point encounter conditions which are outside their natural capabilities. Operation under high load, high temperature, and other hostile environmental conditions for extended periods of time have been found to require the use of additives to augment and supplement the natural lubricating abilities of hydrocarbon oil or grease.
Usually a combination of additive materials are employed in a careful balance to impart anti-wear, anti-friction, extreme pressure, anti-oxidant, anti-foaming, viscosity breakdown resistance, etc., capacity to the oil.
It is known, for example that various dimercapto-thiadiazole compounds are effective anti-wear and friction reducing additives for lubricating oils but they also exhibit corrosivity. To overcome this limitation dimercaptothiadiazol materials have been derivatized with other materials to produce compositions useful as corrosive inhibitors. Thus 2,5-dimercapto-1,3,4-thiadiazole have been reacted with diamines (U.S. Pat. No. 2,910,439), with formaldehyde and diarylamine (U.S. Pat. No. 2,765,289), with unsaturated ketone (U.S. Pat. No. 2,799,652), with unsaturated cyclic compounds (U.S. Pat. No. 2,764,547), and with formaldehyde and alcohol (U.S. Pat. No. 2,850,453) to produce derivatives useful as anti-corrosion additives.
U.S. Pat. No. 4,990,273 discloses an extreme pressure anti-wear additive which is the reaction product of 2,5-dimercapto-1,3,4-thiadiazole with oil solubilizing radicals. Preferably the additive is the reaction product of 2,5-dimercapto-1,3,4-thiadiazole with an aldehyde and a primary or secondary aliphatic or allcyclic amine.
U.S. Pat. No. 4,764,298 discloses an extreme pressure anti-wear additive soluble in lubricating oils which comprises the reaction product of a 2-mercaptobenzothiazole with (1) an aldehyde or ketone preferably having 1 to 10 carbon atoms and (2) ammonia or an amine, preferably an amine containing between 8 and 40 carbon atoms.
It is also known that benzotriazole is an excellent anti-corrosion agent but is of limited utility because of is low solubility in oil, rendering it useless in most lubricating oil applications.
In "The Response to Vapor Challenges of New Microsenser Coatings: Thiadiazole Derivatives" Katritsky et al, Chemica Scripta 1989, 29 315-317, various thiadiazole derivatives are described and their use as coatings for chemical microsensors by spray coating onto A Surface Acoustic Wave (SAW) device is investigated. Among the thiadiazole derivatives described is a benzotriazole-thiadiazole compound of the formula: ##STR1##